Bob Johnson is worried. Two years ago, when he sold his 143-acre Sunrise Resort on the Salmon River in Moodus to the state, he told a reporter that, while he would miss seeing all the returning vacationers, he could take comfort in knowing the summer resort he had known since boyhood could never be "turned into an office park or housing development." In 2008, a developer offered Johnson $5 million for the landmark resort - a swath of rolling meadow and wooded hills dotted with cabins along the sparkling river - but Johnson declined. Instead, in February 2009, he signed a deal with the state for $3.2 million, assured that the 100-year-old retreat, once popular with New York crowds, would remain open space forever. Now, the proposed Haddam land swap - in which the state may trade open space on the Connecticut River to a developer in return for other property - has caused Johnson to question the assurances he was given. "We sold it to the state because they assured us the land would be protected," Johnson said. "We understood it would continue to be used for recreation, but that nobody could build on it. But look what's happening in Haddam. If they can do it with one piece of land, they can do it with another." Johnson's concern is echoed loudly by opponents seeking to block the Haddam swap, which would give 17 acres of state-owned land across the Connecticut River from the Goodspeed Opera House to the owners of an adjacent Riverhouse banquet center. Riverhouse Properties wants to build a hotel and retail complex on that land, and in return would give the state 87 acres it owns in Higganum near Cockaponsett State Forest. The swap is contained in a Senate conveyance bill reintroduced this year by state Sen. Eileen Daily, D-Westbrook, on behalf of Riverhouse Properties. Riverhouse's partners say their development will entice visitors to the area, boosting the regional tourist economy. But groups fighting the swap contend that the state land, with its picturesque views of the river, the old "Swing Bridge" over the river and Goodspeed Opera House on the far bank, is too precious to trade away. Releasing public conservation land for development is a breach of public trust, they say. And they worry about the "chilling effect" the swap could have on future open space donations. Johnson thinks these concerns are well-founded. "If I knew then what I know now, I would have thought differently about selling my land to the state," he said. The 143-acre Sunrise Resort, like the 17 acres in Haddam, was purchased with money from the Recreation and Natural Heritage Trust, a program funded by the State Bond Commission and administered by the state Department of Environmental Protection to buy land that would be added to the state park and forest system. State Rep. Phil Miller, whose district includes Haddam, has joined citizens and environmental groups in opposing the swap, setting up an interesting contest with his former ally and friend, Daily. Miller plans to introduce an amendment that would remove the exchange from the conveyance bill, should the measure pass the Senate. The amendment had 30 sponsors in the House as of Friday, Miller said. "I have heard from many constituents and other citizens from throughout the state that they are concerned that this would set a terrible precedent, by removing land which has been purposefully donated or sold with the expectation that it would remain as conservation land in perpetuity," Miller said in an e-mail to other lawmakers. "I have also heard from several generous donors who have said that should this bill pass, they will never donate another acre ever again." Opponents have been lobbying intensely to secure the votes needed to defeat the bill, and text messages and e-mails have been flying back and forth proclaiming the latest gains and pinpointing new challenges. On Friday, the Connecticut League of Conservation Voters sent an e-mail blast to all legislators, urging them to remove the swap from the conveyance bill, listing more than 20 environmental groups that oppose the proposed Haddam transfer. Middlesex County Chamber President Larry McHugh countered with an op-ed to the media reiterating the chamber's support for the swap, calling the contested land - known as Clark Creek Preserve - "an unused former sand pit" whose redevelopment will create a "tourist destination." Observers said the upcoming vote was too close to call. Meanwhile, the Connecticut River Gateway Commission announced that it is backing away from plans to donate to the state a parcel of conservation land on the Salmon River in Moodus, as a result of the proposed deal in Haddam. This 36-acre tract is just down from Sunrise Resort State Park and the 300-acre Machimoodus State Park, where the Moodus River rushes down through hemlock hills. Gateway Senior Planner J.H. Torrence Downes said the eight-town commission, established years ago to protect the Connecticut River's scenic values, is troubled by the DEP's continued silence on the Haddam swap - in particular newly appointed Commissioner Daniel Esty's refusal to take a position in the matter. In a letter to Esty last week, Downes wrote, "The Gateway Commission, although perplexed by the apparent willingness by the General Assembly to convey state-owned conservation land for private development, is even more troubled by the strategy of silence taken by the Department for what appear to be purely political reasons. It is unclear to the Commission how, even in light of the need for economic development, such an ill-advised, short-sighted position ... could be taken by the state's frontline conservation organization."